WTPZ41 KNHC 160242 RRA

TCDEP1



HURRICANE FERNANDA DISCUSSION NUMBER  17

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062017

800 PM PDT SAT JUL 15 2017



RECENT MICROWAVE IMAGERY, INCLUDING A JUST-RECEIVED GPM OVERPASS,

INDICATE THAT FERNANDA CONTINUES TO HAVE CONCENTRIC EYEWALLS WITH

DIAMETERS OF ROUGHLY 10 AND 45 N MI.  THE EYE HAS BECOME LESS

DISTINCT IN CONVENTIONAL SATELLITE IMAGERY SINCE THE LAST ADVISORY,

AND THE CENTRAL CONVECTION HAS BECOME MORE RAGGED.  BASED ON THIS,

THE INITIAL INTENSITY IS LOWERED TO 110 KT, WHICH IS A LITTLE BELOW

THE AVERAGE OF THE VARIOUS SATELLITE INTENSITY ESTIMATES.  WHILE THE

INNER CORE HAS BECOME A LITTLE LESS ORGANIZED SINCE YESTERDAY, THE

HURRICANE HAS DEVELOPED A LARGE AND SYMMETRIC AREA OF OUTER

CONVECTIVE BANDING.



FERNANDA HAS ABOUT 24 H MORE IN A WARM-WATER, LIGHT-SHEAR

ENVIRONMENT.  THE INTENSITY FORECAST IS BASED ON THE PREMISE THAT

THE CURRENT EYEWALL REPLACEMENT CYCLE WILL FINISH BEFORE THE

HURRICANE LEAVES THE WARMEST WATER, AND THUS IT CALLS FOR SOME

RE-INTENSIFICATION DURING THAT TIME.  FROM 24-96 H, FERNANDA

SHOULD REMAIN IN A LIGHT SHEAR ENVIRONMENT, BUT WILL MOVE OVER

DECREASING SEA SURFACE TEMPERATURES AND INTO A DRIER AIR MASS.

AFTER 96 H, THE CYCLONE WILL ALSO ENCOUNTER SIGNIFICANT WESTERLY

SHEAR.  THE INTENSITY FORECAST THUS CALLS FOR STEADY TO RAPID

WEAKENING AFTER 36 H.  OVERALL, THE NEW INTENSITY FORECAST IS A

LITTLE HIGHER THAN THE MODEL CONSENSUS FOR THE FIRST 36 H AND NEAR

THE CONSENSUS AFTER THAT.



FERNANDA IS NOW MOVING 285/12, STEERED BY A MID- TO UPPER-LEVEL

RIDGE TO THE NORTH AND NORTHEAST.  A WEST-NORTHWESTWARD MOTION IS

EXPECTED TO CONTINUE FOR THE NEXT SEVERAL DAYS WHILE THE HURRICANE